1. Field of Invention
The present invention relates to a display device and a light adjusting method thereof.
2. Description of Related Art
A conventional projection type display device can have the following problems. Because of leaked light or stray light that occurs in several optical elements constituting an optical system, sufficient contrast is not obtained. That is, the displayable brightness range (dynamic range) is narrow, and image quality is inferior as compared to an existing image monitor using a cathode ray tube (hereinafter, referred to as CRT). Although quality improvement of an image is sought by various image signal processes, it is impossible to exhibit sufficient effects because of a fixed dynamic range.
As a solution for the problems associated with such a projection type display device, namely, a method of expanding the dynamic range, it can be considered to change the flux of a light component incident to the light modulating means (light valve) according to an image signal. The most convenient method for realizing it is to change the light output intensity of a lamp. A method of effecting control of the output light component of a metal halide lamp in the projection type liquid crystal display device is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 3-179886. Further, because light emitting spectral variations by which output variation is accompanied in the white light source occurs, effecting the display by correcting it has been proposed, for example, in Japanese Unexamined Patent Application Publication No. 11-296127.